TABLE 1.
ATPase activities of PA700 and PA700 subcomplexes
PA700 and PA700 subcomplexes were purified as described in the text and assayed for ATPase activity by the Malachite green method. PA700 (2 or 6 μg/assay, as indicated) or PA700 subcomplexes (4 μg of an individual subcomplex or 4 μg of each subcomplex for combinations) were assayed for ATPase activity in the presence (+) or absence (−) of 15 μg of 20 S proteasome after preincubation reaction for reconstitution, as described under “Experimental Procedures.” Data represent mean values of triplicate assays (±S.E.). Similar results were obtained in at least three independent experiments for each condition. Similar results also were obtained with an independent experiment using a radiometric assay of ATPase activity.
| Protein | ATPase |
|
|---|---|---|
| −20 S | +20 S | |
| pmol Pi/min/μg protein | ||
| PA700 (2 μg) | 26 ± 3.7 | 32 ± 4.4 |
| PA700 (6 μg) | 25 ± 1.8 | 29 ± 2.1 |
| PS-1 | 0 | 0 |
| PS-2 | 0 | 0 |
| PS-3 | 0 | 0 |
| PS-1/PS-2 | 0 | 0 |
| PS-2/PS-3 | 0 | 0 |
| PS-1/PS-2/PS-3 | 11.5 ± 1.6 | 13.3 ± 2.3 |